Dredge



June 29, 1943.

A. D. CLEMENTS DREDGE Filed July 18, 1941 2 Sheets-Sheet l NvEN-roR Ar/hur 0. C/gmen/s BY Jun 29, 1943. A. D. CLEMENTS DREDGE Filed July 18, 1941 2 Sheets-Sheet 2 Patented June 29, 1943 UNITED STATES PATENT OFFICE 6 Claims.

My invention relates to means for recovering subaqueous values, for example gold recovery by alluvial dredging. The invention is especially concerned with a dredge for operation on relatively less extensive ground which justifies only a relatively inexpensive type of mechanism. There are many localities in which the standard bucket line dredge is not feasible for the reason that it requires too great a capital investment. The operating characteristics of a bucket line dredge are desirable but the cost of installing and maintaining the dredge is prohibitive. Under such circumstances various other expedients have been utilized, among them the so-called doodle-bug or drag line operation, in which a boom is rested upon the bank of the dredge pond and is also mounted on a dredge float and a drag line bucket is cast by the operator laterally as well as forwardly and then returned to the recovery mechanism on the float. This type of operation is not satisfactory where there is a high bank or where the bank is subject to caving since it very substantially limits the extent of the area which can be covered. Also it requires a highly skilled operator to cast the drag line bucket properly and not only in manipulating the structure generally, but especially in returning the bucket to the dredge hull and the value-saving mechanism for there is a good deal of spillage which is lost since it is scattered all over the bottom of the dredge pond.

It is therefore an object of my invention to provide a dredge which is inexpensive in first cost and in operating cost.

Another object of my invention is to provide a dredge which can be operated by semi-skilled labor.

Another object of my invention is to provide a dredge which can dredge to a great depth below the surface of the pond and can handle ground in which there is a high bank.

Another object of my invention is to provide a dredge in which any values lost overboard are concentrated in an area from which they can readily be regained.

The foregoing and other objects are attained in the embodiment of the invention illustrated in the drawings, in which- Fig. 1 shows, partly in diagrammatic form, a dredge constructed in accordance with my invention. This is the preferred form for all around use.

Fig. 2 is a plan of a structure shown in Fig. 1.

Fig. 3 is a view similar to Fig. 1 but shows a modified form of dredge which is especially useful where the dredging must be done in a relatively deep pond. The depth of the water illustrated in the drawings is only diagrammatic and is not to scale.

Fig. 4 is a plan of the structure shown in Fig. 3.

In its preferred form the dredge of my invention includes a water borne hull which is extended or provided with a boom to support a forward cable guide, the extension defining a central well through which a drag line bucket can be moved from the bottom of the dredge pond. On the hull is a superstructure, including a hopper leading to the customary value saving mechanism and above the hopper is a second cable guide so that two lines extending from the drag bucket through the well pass respectively about the cable guides and when appropriately operated serve to bring the loaded drag bucket through the well into discharging location over the hopper, and then to return the drag bucket through the well to a location below the drag hull for a subsequent dredging cycle.

In the form of the invention shown in Figs. 1 and 2 particularly, the operation is conducted in a dredge pond 6, located in value bearing land I defining the dredge pond bottom 8 and a bank 9. On the pond 6 is disposed a dredge hull ll fabricated in any convenient way, usually of structural steel plates reinforced with suitable angles and channels, and in plan defining substantially a rectangle but having a reentrant portion l2 bounding a central free space or well It. which is unobstructed by any portion of the dredge mechanism.

On the hull is disposed a superstructure M, which assists in supporting a standard value recovery apparatus including a hopper l6 disposed centrally of the hull ll andhaving an open top to receive material. The hopper discharges into a revolving screen ll in the customary fashion and from the screen the material is put through the value saving apparatus not illustrated because it is well known to those skilled in the art.

For removing material from the pond 55 above and below the water line I provide a drag bucket I8 of any convenient design which itself is standardized and includes a chain connection 19 extending to a pulley 2| around which is trained a short cable 22 connected at one end to the arch 23 of the drag bucket l8 and at the other end connected to the outboard terminus of a chain 24 which itself is connected to the drag bucket Hi.

In order to advance the drag bucket it into the material underlying the pond, the chain 24 is connected to a cable or line 26 which extends upwardly and forwardly around a cable guide 21 preferably constituted by a pulley journalled on a shaft 28 carried in the forward converged portion of a boom 29. The boom itself is conveniently fabricated of structural shapes and is constituted by bifurcated members, having a function piece 3I at the forward end but spreading rearwardly to afford a continuation of the uninterrupted well I3 and to be connected by suitable pivots 32 on the divided forward portion of the hull I I. Ordinarily the boom 29 is set into an adjusted position for operation in connection with the particular bank that the dredge is encountering and is then held for a protracted period in that location,

In order to facilitate such positioning of the boom and to hold it rigidly when it has once been put in position, I provide a pivotally connected strut 33 joined to the junction piece 3| and extending upwardly and rearwardly to a connection by a pivot pin 34 with part of the superstructure It. A series of apertures 36 in the strut 33 make it possible to lift the boom 29 to virtually any desired height or to drop the boom to any desired depth within the capacity of the structure and to correspond with the height of the bank 9 and to hold the boom in position for operation.

- The locking of the strut 33 in position likewise looks the cable guide 23 in appropriate position so that the cable 26 which extends there-around is appropriately guided centrally of the hull to a second cable guide which is one of a pair of pulleys 3'3 disposed centrally of the mechanism and at the apex of the superstructure I ll, from whence the cable 2t passes around a cable guide 38 in the form of a winch drum driven by any suitably controlled source of power, diagrammatically illustrated at 39. An operator standing adjacent the winch drum 38 where he can observe the entire operation manipulates the drum 38 so that the drag bucket it is advanced or permitted to fall and retract.

Also there is provided a second line for controlling the drag bucket. A cable 4| constitutes an extension of the chain it and passes upwardly through the well It around a third cable guide 42 in the nature of a pulley supported by the superstructure and disposed forwardly of the hopper l6 and centrally of the hull. The line lI then passes around the other of the pair of cable guides 3i and to a cable guide in the nature of a winch drum 33 independently controlled by the operator but driven from the same source of power.

By appropriately operating the two lines 26 and ll separately or in conjunction in accordance with the usual manner of operating drag buckets, the operator can advance the bucket I8 into and through the value bearing material 7 until a load is obtained and then lift the drag bucket upwardly in a general upright and non-spilling position through the well 53 to a location over the hopper I6 whereat the dredge bucket is by proper manipulation of the lines 26 and ll inverted to discharge its contents into the hopper. The discharged contents pass through the remaining value recovering part of the structure. The drag bucket is returned through the well. I3 to its previous location or to a new location adjacent thereto and the dredging cycle is repeated.

The hull II is provided with a suitable set of bow and stern lines, not shown because they are standard in dredge operation, for holding the dredge against the bank or adjacent thereto in any selected position and for swinging the dredge laterally to either side of its previous location. Since repeated operations of the dredge are accomplished with the hull in a single location, the bucket I8 repeatedly traverses its path and repeatedly advances in the same general vertical plane into the bank 9. The bucket also is lifted from its sub-aqueous position to the hopper in substantially the same vertical plane so that any spillage from the bucket is readily recovered during a subsequent cycle.

The operator does not swing the bucket laterally or traverse the bucket while it is being returned to position and hence only semi-skilled labor is necessary to operate the winch drums 43 and 38. There is no substantial restriction on the depth to which the bucket I8 can be dropped since that only means paying out more of the cables 26 and M. Also within reasonable limit there is no curtailment of the height of the bank 9 with which the mechanism can operate. Since the structure is all entirely supported on the water borne hull I I, whether or not the bank 9 is capable of supporting weight is entirely immaterial because neither the boom 29 nor the strut 33 rest thereupon.

Especially for use where a great depth is to be dredged and where additional buoyancy is desirable in the forepart of the hull because of the added weight concentrated in such location, I preferably provide the arrangement shown in Figs. 3 and 4 which is very similar to that previously described in most aspects [but in which the dredge hull 5i itself is extended as far forwardly as necessary in order to avoid a separate boom and to provide additional buoyancy in the forepart of the structure. The hull M is reentrant to provide a central Well 52. A superstructure 53 of the same type as before is utilized except that there is no boom although reinforcing beams 54! extend forwardly from the superstructure along either side of the well 52.

Supported on the superstructure is a hopper 56 with associated mechanism as before, and adapted to cooperate therewith is a drag bucket 5? of exactly the same type and having the same connections. From the drag bucket extends a first line 55 which passes around a cable guide 58 located at the forward end of the hull 5| straddling the well 52 and supported on the reinforcing beams 54. In this instance the cable guide 58 is a winch drum which is independently and individually driven through gears 59 from a source of power, not shown, which actuates drive shaft 8!. Also independently and separately driven through the gears 59 is a second Winch drum 62 similarly straddling the well 52 and mounted on the beams 54. From the second drum a line E53 passes around a second cable guide 64 disposed at the apex of the superstructure 53 and then passes around a third cable guide 65 located just in front of the hopper 56 centrally of the hull and finally terminating on the drag bucket 57.

The operation of the drag bucket is performed in exactly the same way as previously described, that is, from the floor of the pond up through the well 52 to discharge into the hopper 56 and then return. The operator is stationed at or adjacent the winch drums 58 and 62 in a better position to observe the operation of the drag bucket 51 itself. With this design more weight is concentrated in the forward portion of the dredge hull but the hull itself is water borne at the forward portion of the structure so that sup-' port is provided where it is needed. The general operating characteristics of this second form are substantially the same as the first although it appears to be better adapted for deep operation.

In both forms of the invention there is provided a dredge which is relatively inexpensive in first cost and in upkeep expense, which does not spill or lose the values where they cannot be readily recovered, which is susceptible to operation at virtually any reasonable depth and with any reasonable height bank, is entirely a self-contained and self-supporting unit and one which for the most part is constructed of readily available components which can be operated by only semiskilled labor.

I claim: I

1. A dredge comprising a hull having a longitudinal well therein open at its forward end, a hopper supported on said hull at the rear of said well, a cable guide, means for supporting said cable guide on said hull in advance of said hopper and adjacent the forward end of said well, a second cable guide, means for supporting said second cable guide above said hopper, a drag bucket, lines trained around said cable guide and said second cable guide, passing into said well from the same side thereof and fastened to said bucket, and means on said hull for operating said lines.

2. A dredge comprising a hull having a longitudinal well therein open at its forward end, a hopper supported centrally of said hull at the rear of said well, a cable guide, means for supporting said cable guide centrally of said hull in advance ofsaid hopper and adjacent the forward end of said well, a second cable guide, means for supporting said second cable guide centrally of said hull above said hopper, a superstructure on said hull, a third cable guide on said superstructure disposed centrally of said hull and in front of said hopper, a drag bucket, a line extending from said bucket through said well from the bottom thereof and over said first cable guide, a second line extending from said bucket through said well from the bottom thereof and over said second cable guide, said second line extending around the forward portion of said third cable guide, and means for operating said lines.

3. A dredge comprising a hull, a hopper on said hull, means for guiding a line disposed in advance of said hopper, means for supporting said line guiding means from said hull and leaving a well between said line guiding means and said hopper, a drag bucket, a line adapted to extend from said bucket through said wel1 from the bottom thereof to said line guiding means, a second line adapted to extend from said bucket through said well from the bottom thereof and adjacent said hopper, and means for operating said lines.

4. A dredge comprising a hull including means defining a re-entrant well in the bow of said hull, a line guiding means disposed centrally of said well in the bow of said hull, a hop-per mounted centrally of said hull aft of saidwell, a second line guiding means arranged above said hopper, a third line guiding means arranged centrally of said hull in front of said hopper, a drag bucket, a line adapted to extend from said bucket and through said well to said first line guiding means, a second line adapted to extend from said bucket through said well and over the forward portion of said third line guiding means to said second line guiding means, and means for operating said lines.

5. A dredge comprising a hull having a longitudinal well therein, a first cable guide disposed on said hull above and at the forward end of said well, a hopper on said hull above and at the rearward end of said well, a second cable guide on said hul1 above said hopper, a third cable guide on said hull ahead of said hopper and at the rearward end of said well, said well in the longitudinal distance between said first and said third cable guides being uninterrupted, a drag bucket adapted to pass through said well, a first line extending from said first cable guide through said well from the top to the bottom thereof and to the front of said drag bucket, and a second line extending from said second cable guide over the forward portion of said third cable guide through said well from the top to the bottom thereof and to the rear of said drag bucket.

6. A dragline dredge comprising a hull having a longitudinal well in the forward end thereof, a dragline guide mounted on the hull above the forward end of said well, a material receiver mounted on said hull, a bucket line guide mounted on the hull above the rear end of said well, a bucket, a dragline engaging the front guide and passing through said well and connected to said bucket, a bucket line engaging the rear guide and passing through said well and connected to said bucket, and means for oper ating said line for lifting said [bucket through said well to said material receiver.

ARTHUR D. CLEMENTS. 

